Syphilis, similar to most other sexually transmitted infections, disproportionally affects females more than males, including the risk of adverse outcome of pregnancy and infection in foetus.To describe and analyse all cases of syphilis among female patients (pregnant and non-pregnant) treated in Bialystok, Poland in 2000-2015.Retrospective analysis of sociodemographic, epidemiological and clinical characteristics of pregnant and non-pregnant syphilis-positive females.From 2000 to 2015, 47 females were treated for syphilis: 17 (36.2%) were pregnant and 30 (63.8%) non-pregnant. The majority of patients in both groups were residents of urban areas (64.7% and 73.3%, P=0.6), and were married or in a long-standing relationship (94.1% and 60.0%, P=0.01). At least five lifetime sexual contacts had 17.5% of pregnant and 3.3% of non-pregnant females (P=0.04). The steady partner was the most probable source of infection in both groups (76.6% and 66.6%, P=0.4). Early latent syphilis was the most frequent stage of the disease in the pregnant women (94.1%) and secondary syphilis in the non-pregnant females (43.3%). In 58.8% of the pregnant females the first serological test for syphilis was performed after 10th week of pregnancy and nearly half of them did not present to any follow-up visit after treatment. In about one third of patients sexual contacts were not examined.Syphilis among females, especially pregnant ones, remains a problem in North-East Poland. Syphilis screening is frequently conducted too late in the pregnancy, increasing the risk of infection in the foetus. Pregnant females frequently do not attend follow-up visits. Contact notification should also be improved.